NAME
erfc, erfcf, erfcl - complementary error function
SYNOPSIS
#include <math.h>
double erfc(double x);
float erfcf(float x);
long double erfcl(long double x);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
erfc(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE || _ISOC99_SOURCE; or cc -std=c99 erfcf(), erfcl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600|| _ISOC99_SOURCE; or cc -std=c99
DESCRIPTION
The erfc() function returns the complementary error function of x, that is, 1.0 - erf(x).
RETURN VALUE
On success, these functions return the complementary error function of x, a value in the range [0,2].
If x is a NaN, a NaN is returned.
If x is +0 or -0, 1 is returned.
If x is positive infinity, +0 is returned.
If x is negative infinity, +2 is returned.
If the function result underflows and produces an unrepresentable value, the return value is 0.0.
If the function result underflows but produces a representable (i.e., subnormal) value, that value is returned, and a range error occurs.
ERRORS
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
| Range error: result underflow (result is subnormal) | |
| An underflow floating-point exception (FE_UNDERFLOW) is raised. | |
CONFORMING TO
C99, POSIX.1-2001. The variant returning double also conforms to SVr4, 4.3BSD.
NOTES
The erfc() functions are provided to avoid the loss accuracy that would occur for the calculation 1-erf(x) for large values of x (for which the value of erf(x) approaches 1).
SEE ALSO
COLOPHON
This page is part of release 3.23 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.
